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You Asked: Muscle vs. Fat?

Dear Fit Sugar,
I'm on a mission to lose that last 10 pounds, which has been so difficult, and I'm training for a half-marathon as well. I eat well and exercise a lot — cardio almost every day and strength training five days a week. I've always heard that muscle weighs more than fat, but after I reached a plateau, I've found that I've been gaining weight. Not much, just a pound or two, but still gaining weight. How do we know when weight gained is added muscle mass, and when it means we need to reevaluate the calories we consume? I'm frustrated that all the hard work only turned into a weight gain.
—Confused and Frustrated

This is a common source of frustration and confusion, but I think I can help clear up a few questions. To see what I have to say about muscles and fat, just


Losing weight is not a simple task, and it is important to remember that it is not really pounds you want to lose, but fat. You want to lose fat and gain lean muscle tissue. People often say that muscle weighs more than fat, but that is a misstatement. Muscle is actually more dense than fat, so a pound of muscle takes up less space than fat. Another way to look at fat versus muscles is that a cubic inch of muscle will weigh more than a cubic inch of fat. Muscle is about 18 percent more dense than fat.

Using weight to determine the health of our bodies or our fitness level is not really accurate. What you want to measure is your body fat percentage, and you can do so with a scale designed for that purpose, or have it measured in a more expensive, but more accurate way. While you say you are gaining weight, I am wondering if your clothes are getting tight, which would be an indicator that you're gaining muscle and fat instead of just muscle. Sometimes something as simple as your jeans feeling tight can be the signal you need to fine-tune your weight-loss efforts.

When you hit a plateau, it is a good idea to look at both what you are eating and how you're exercising. Although it sounds like you're exercising a lot, you should make sure to add interval training and speed work to your running routine to add an extra calorie burn. Your muscles might also have hit a plateau with your strength training program. You want to mix up your strength training routine every six weeks to two months, and if you're not working your muscles to exhaustion you need to increase the amount of your weights. Make sure you're eating a well-balanced diet to support your running. Here is more advice for pushing past your weight loss plateau.

Also, it is common to have fluctuations in your weight from day to day, and even week to week.

Good luck on your half marathon!


Join The Conversation
bekahnz bekahnz 6 years
i agree.... when you're feeling on top of the world, you seem to feel better and look better... i always use calipers and never weigh myself
fitjourney fitjourney 6 years
Ditch the scale, and interpret the measuring tape. You can have a 36" booty, or a 36" saggy butt. A pair of jeans or a favourite party dress are the best way to check out your progress. And then, stop looking at your body. Notice how you're feeling . . . energy, positive, stronger?
pandacn pandacn 8 years
measuring tape is a great idea, but especially in terms of belly fat, I feel like i'm gaining muscle, but my abs still aren't defined because it seems impossible to lose that top layer of fat!
ilanac13 ilanac13 8 years
i read something here the other day about interval training and i'm starting to work that into my routine in the hopes that it'll put me back on track to what i'm trying to lose.
Red-Sharpie Red-Sharpie 8 years
If it's indeed fat and not muscle... When was the last time you took a break and how much are you eating? It sounds like you might be exercising *too* much. If you're doing full-body strength training on all those 5 days it's definitely too much. When you overexercise or don't eat enough you overstress your body and elevate your cortisol levels. Your body will see this as a message that you need to store fat to protect yourself (along with other bad things). If this is the case you can push past it by upping the intensity but this will just stress your body more and make your weight loss impossible to maintain (I've been there). At that level of training, I'd guess you should be eating AT THE VERY LEAST 1800 cal/day. I suggest you take a week off exercise and have a cheat meal, if you haven't in a while. Also, make sure you are getting plenty of sleep. When you come back to exercise not only will you be more refreshed but you should be able to push past your plateau as well (assuming your weight goal is healthy to begin with).
Spectra Spectra 8 years
I'm going to second everyone else who said to use a tape measure or go by how your clothes fit. Your weight can fluctuate up to 5 lbs a day naturally, based on a lot of different factors. If you drink a pound of water, you'll weigh a pound more even though water has no calories. So yeah, what I did when I was losing weight was to hit the mall once a month and see what size jeans I could fit into at that time. It was really fun to see how many sizes I lost each month.
rafaela-losardo rafaela-losardo 8 years
I think the scale is often unfair to women, measuring tapes don't fail if we're bloated or if we gain muscles :wink:
yasume yasume 8 years
I lost alot of weight and did not know how much I weighed because I didn't use the scale. I measured by how my clothes fit and that was enough for me. I would use the tape measure on occasion but not too often. I would just measure my waist and would make a mental note. I was definitely losing fat and gaining muscle. I am now about 150lbs(height-5'9") but I look smaller according to what others have told me. Muscle takes up less space then fat.
GlowingMoon GlowingMoon 8 years
I just look at how my clothes fit. For me, it's easy for me to tell with jeans and shorts.
diffraction diffraction 8 years
I've read that people can sometimes gain weight or hold on to weight while training for half-marathons/marathons... Some info...
Fitness Fitness 8 years
A measuring tape is a great idea. I can never find one in my house — for some reason my daughters love to play with mine. While I can remember how much I weigh from week to week, since it is just one number, I am not sure I could track more than one measurement. Do you all just measure your waist? Or other areas too? Do you write the measurements down or just keep track in your head.
nycactres nycactres 8 years
I never weigh myself. I'm a size 4/small and 140 lbs. Muscle definitely weighs more than fat.
sushibananas sushibananas 8 years
I measure my weight gain/loss simply by how my clothes fit. It gets depressing standing on a scale and not seeing those numbers drop like you want them too. But when you easily slip into your jeans (not wiggle to get them over those hips!) oh man, that's an awesome feeling!!!
runningesq runningesq 8 years
measuring tape, definitely -- and -- how your clothes fit!!
aprilmayjune4 aprilmayjune4 8 years
Definitely a fan of the measuring tape. Weight has so many variables.
tlsgirl tlsgirl 8 years
Yeah, I just use a measuring tape. I feel like it's the most accurate, and since it takes a few minutes to do measurements, and I usually have to look for my tape, it keeps me from obsessing.
sundaygreen sundaygreen 8 years
Throw out the scale and buy a measuring tape instead.
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